Improve test framework: tfw_cmp_version()

Also add unit tests for test framework itself
Improve test defs: setup_curl()

Replace setup_curl_7() function in separate test scripts with a single,
general setup_curl() function in testdefs.sh which takes the minimum
version number as its argument.
Refactor setup for 'rhizomeops' test script
Improve test defs: setup_jq()

For test fixtures that need the jq(1) JSON filter utility
First HTTP RESTful interface tests
Merge branch 'development' into 'naf4'
Add str_to_int() and str_to_uint()
Rename http_header_complete() to is_http_header_complete()
Add 'debug.rhizome_httpd' config option
Rewrite HTTP server
Add alloca_poll_events() macro
Add 'strlen' argument to strn_fromprint()
Use size_t in Rhizome store functions
New header file "fdqueue.h"

So that "http_server.h" does not have to include "serval.h" which
creates a circular dependency.

Remove the __SERVALDNA__HTTP_SERVER_IMPLEMENTATION hack from
"http_server.h"
Improve str_to_int() et al

Always set *afterp to point to the first invalid character
even if conversion fails
Add str_tolower_inplace() function
Add alloca_strdup() macro
Make logging D and T macros into expressions

So they can be used in-line in multi-line logical expressions.
Fix basic bugs in new HTTP server code

All 'rhizomeprotocol' HTTP tests still fail
Fix a couple more bugs in new HTTP server code